A tanker trailer 10 is shown in FIG. 1 and includes a tank 12 having an interior volume at least partially filled with a liquid 14 for transportation. As shown, a manhole cover 18 is provided and coupled to a collar that defines an opening in the top of the tank 12. The manhole cover 18 is pivotally attached to the collar so that an operator may open the cover to access the interior of the tank, typically for cleaning, inspection or repair.
The tank 12 also includes one or more access assemblies 20A, 20B each including a cap 22 coupled to respective collars 24 that define openings to the interior to the tank 12. As shown in FIG. 2, these prior art caps 22 have an internal thread mating with an external thread of the collar 24, so cap 22 is screwed onto the collar 24. When used as caps for an external vent fixture, when the tanker trailer 10 is transported to a desired location where the liquid 14 is to be emptied from the tank 10, the caps 22 must be removed from the collars 24 to allow for ambient air to flow into the tank as liquid is drained from the tank 12. In addition, the caps 22 may he removed so hoses may be attached to the collar 24 to fill the tank with fluid to be transported, or to inject cleaning fluids for cleaning an interior of the tank 12.
Ladders 16 are typically mounted to the trailer 10 and tank 12 at a location that is readily accessible to the manhole cover 18, which is often at a midsection of the tank 12. Accordingly, a catwalk 30 runs along the top of the tank 12, which an operator traverses to access the caps 22. The act of climbing the ladder 16 and traversing the catwalk 30 alone are inherently dangerous, and this inherent danger is compounded when the operator must carry a large wrench tool to remove the caps 22, which may be about three to five inches in diameter. Moreover, in removing the cap 22 the operator is applying torque to the wrench and pivoting on the top of the tank 12 further risking slipping and falling off the tank 12. While systems are available to remotely open and close manhole covers, no such systems exist, nor are adaptable, to open and close the above described caps 22.